Related Experiment Video
Updated: Feb 7, 2026

Synovial Fluid Analysis to Identify Osteoarthritis
Published on: October 20, 2022
Acute apatite podagra with negative birefringent spherulites in the synovial fluid
F Beaudet1, R de Médicis, P Magny
1Division of Rheumatology, Hôpital du Sacré-Coeur, Université de Montréal, PQ, Canada.
Abstract:
We describe a young male patient who presented with acute podagra after jogging activity. He had no underlying pathology. Polarized light microscopy of the synovial fluid from his first metatarsophalangeal joint revealed numerous negative birefringent spherulites about 6 microns in diameter, presenting the typical appearance of Maltese crosses. The molar calcium/phosphorus ratio of these spherulites as determined by X-ray energy dispersive analysis was virtually identical to that of synthetic or pathologic apatite.
Related Concept Videos
Structural Joints: Synovial Joints
Development of the Limb Synovial Joints
The mesenchymal stem cells differentiate into chondrocytes that form the hyaline cartilage, and later the cartilaginous model of the bone. This model further transforms into a bone. This process is known as endochondral ossification.
During development, the limbs...
Negative Regulator Molecules
Positive, Negative, and Zero Work
The Fluid Mosaic Model
Negative and Cognitive Symptoms of Schizophrenia
Negative Symptoms
Negative symptoms of schizophrenia manifest as deficits in normal emotional and behavioral functioning, profoundly impacting daily life. Individuals with schizophrenia often display a flat affect, characterized by a near-total absence of emotional expression,...

